How to Calculate 2018 Oregon State Income Tax by Using State Income Tax Table

4. Check the 2018 Oregon state tax rate and the rules to calculate state income tax

5. Calculate your state income tax step by step

6. If you want to simplify payroll tax calculations, you can download ezPaycheck payroll software, which can calculate federal tax, state tax, Medicare tax, Social Security Tax and other taxes for you automatically. You can try it free for 30 days, with no obligation and no credt card needed.

If a state income tax certificate has not been processed or if a valid state exemption code is not present, the Federal exemption code will be used in the computation of state tax or if an invalid marital status (other than S, M, or H) is present with the number of state exemptions, the highest Oregon withholding rate (Single) with the number of exemptions will be used in the computation of state tax.